Plywood tubing



Jime 16, 1942. C. FARNY 2,286,267

PLYwooD TUBING l Filed July 25, 1946 5 sheets-sheet 1 HW q 1 N VEN TOR. Urk/.4 f/wvx June 16, 1942.4 c. FARNY PLYWOOD TUBING Filed July 25, 1940 3 sheets-sheet 2 l l l l June 16, 1942.

c. FARNY PLYWOOD TUBING Filed July 25, 1940 3 Sheets-Sheetl 3 l l' INVENTR. l BZWWW/ I ,/.MM mm f w L m f Patented June 16., 1942 nuire PLYWOOD TUBING Cyril Farny, St. Charles, lll., assignor to The Rudolph Wurlitzer Company, Cincinnati, Ohio,

a. corporation Application July 25, 1940, Serial No. 347,382

2 Claims.

This invention relates to a multi-ply wood veneer structural tubing having many applications and uses, such as structural rods, beams and the like, airplane parts, conduits, containers and shelters.

Essentially, the invention pertains to improvements in tubing of this character, such as to substantially strengthen it as well as lessen its `cost of production. The invention consists in spirally winding the strips of wood veneer in opposite directions with respect to each alternate in the nature of a steam pipe about which two or more layers of wood veneer strips are spirally wound with the windings and grain of each suc- .cessive layer extending in opposite directions.

In this form and under tension they are bonded with an intermediate coating of a thermosetting resin glue. After the Winding of the strips has been completed, they are subjected to conforming pressure and heat which may be developed by passing steam through the pipe. Following such treatment of pressure and heat, the veneer winding is slidably removed longitudinally of the pipe, resulting in a tubular structure of great strength, lightness vand durability, having many advantageous uses.

A further feature of the invention resides in winding and pressing the oppositely directed spiral strips to develop a localized peripheral rib or bulge for reinforcement and interlocking purposes. Thus, a sealing plug, or cap, reinforcing and nailing disks or the like, may be lncorporated in the tubing or provided for. Such bulge may also be in the form of flared ends to provide interlocking joints.

Another feature of the invention resides in the ability of the oppositely directed spiral windings to form a continuous unbroken tubing of great length, such as a cross country pipe line. Also such windings permit of tapered tubing to provide for telescoping ends or sections.

Such wood veneer tubing may be produced at low cost and be impervious to the action of water, heat and cold, and resistant to fire. 'Also, for structural purposes, it will-'not be affected by termites.

vorable than most metals, including aluminum.

The relation of its strength to its e lightness and thickness of material is more favThus, it is found to be actually stronger than aluminum tubing of the same thickness. As a result of the above qualities, its uses would appear to be extensive. structurally it is adapted Afor use as struts, tie rods, beams and joists. It may be used vas piping for fluids, either above or underground and to that end may be made con-'- tinuous without joints on the job. In various forms it may be produced for use as containers, such as cups, tumblers and the like, and larger diameters for sections of airplane fuselage and wings, as-well as culverts, shelters and many other useswhich need not be here enumerated. f

The full nature of the invention-will be 'understood from the accompanying drawings ,and the following description and claims:

Fig, 1 is a perspective view showing a section of finished tubing with a portion ofthe outer veneer being broken away to disclose the inner layer of veneer. Fig. 2 is a perspective view of the first andsecond layers of veneer wound upon an inner form or core with a portion of the outer layer being broken away to disclose a portion of the inner layer. Fig. 3 illustrates one form of a removable steam pipe associated with steam ttings about which the veneer strips are being wound. Fig.y 4 is an enlarged view of a section of the steam pipe showing the clamping members in section. Fig. 5 is'a section taken on the line 5 5 of Fig. 4. Fig. 6 shows a modified form of tubing with reinforcing ribs and joint forming ends. Fig. 7 is a section of pipe or core upon which the tubing of Fig. 6 is formed. Fig. 8 Shows a joint connection between two tubes, as illustrated in Fig. 6, with the upper portion thereof shown in section. Fig. -9 is the same as Fig. 8, illustrating the use of an internal plug at the pipe joints. Fig. 10 shows a vertical section through a. portion of the tubing having an inner reinforcing plugformed .therein and clo-v tapered form. Fig. 16 is a perspective view illustrating a spring-steel or rubber external pressure exerting member. Fig. 17 is the same as Fig. 5 showing a resilient bag within the clampin members; p

In the drawings there is shown for purpose of illustration, and as one example of the invention, a tube II) comprising an inner layer formed of a spirally wound plywood or wood veneer strip II having its abutting edges secured and sealed by the application of a thermo-setting resin glue. Surrounding the inner layer and spirally wound thereabout in the opposite direction, there is a second layer formed of a wood veneer or plywood strip I2 having the adjacent edges similarly sealed and secured by such glue, and wherein a coating of such glue is provided between the two layers so that they will rigidly adhere together and be inseparable.

Depending upon the strength and size of the tubing to be produced, any desired number of layers may be applied, there being only two such layers illustrated herein for convenience. Thus, the tubing may be of two ply, as shown, or three or more plies, if desired, each ply or layer having its veneer strip spirally wound in the opposite direction to that of the next underlying ply. Between each ply a coating of thermo-setting resin glue is applied, as well as along the edges of the spirally wound strips of each ply. Similarlypwhere desired, each ply may be covered by a fabric indicated at I3, which fabric is impregnated with the said glue to provide further strengthening and moistureprooiing of the inner liner.l However, in many uses of the tubing such fabric liner need not be employed.

As shown in Figs. 2 and 3, there is provided a steam pipe I4 which serves as an inner core or form for receiving the first wrapping of the veneer strip II. The ends of the veneer strips are clamped adjacent the end of the pipe I4 by a clamp I5. As illustrated herein, in the two ply tube both strips may be secured at the same end of the pipe and simultaneously wound thereabout. It may, however, be desirable, and particularly wherein a large number of layers are employed, to clampthe ends of the strips at different ends of the pipe and wind them separately. It is not desirable that the strips be tightly wound upon the pipe; in fact, it is preferable to permit a certain amount of looseness in order that the finished tubing may be conveniently removed from the pipe by sliding the same oi of one end thereof. Before the winding or after each under strip is wound, itr isA treated with an application of thermo-setting resin glue over its outer or exposed surface.

As shown herein the pipe` is held stationary While the veneer strips are spirally wound thereabout. However, this process may be reversed, wherein the pipe is rotated to effect the spiral ,winding of the strips thereabout.

The pipe I4 is herein shown as removably connected and supported at one end by a steam coupling I6 connected with a steam pipe I1 and controlled by a steam valve IU. The opposite end of the pipe is removably connected and supported by a steam joint I9 on a steam outlet connection 20.

After the spiral wrapping of the veneer strips has been completed, the clamps 2| are brought to bear against opposite sides of the veneer tubing so as to embrace it, as shown in Figs. 4 and 5. The tubing is thereby subjected to a pressure of substantially 100 pounds per square inch, while at the 'same time giving the desired form to the exterior surface thereof. Any suitable exterior pressure applying means may be employed, that herein illustrated for example being in the nature of an oversize pipe split longitudinally with its opposite split sides mounted upon connecting rods 22 operating in the oppositely-disposed steam chests 23 through the medium of pistons 24 secured to said rods.

Substantially simultaneously-with the application of the external pressure, heat is applied by passing steam through the pipe I4 acting as a core about which the veneer is wrapped. It is preferable to bring the temperature of the pipe and, therefore, the internal surface of the tub- :ng up to approximately two to three hundred degrees. Under this temperature andthe applied external pressure, the outer finished surface of the tubing will'take itsfinal form and the thermo-setting resin glue will become finally set. After being subjected to such temperature and pressure, the clamps are removed, the pipe I4 is disconnected from its steam coupling and joint, whereupon the tubing which has been loosely wound thereon may be readily slid off of one end.

As illustrated in Figs. 6 and 7, the tubing IIII may be similarly formed but with spaced reinforcements in the form of collars I I3. Thus,

the pipe I4 may be provided about its surface with a reinforcing collar built up of plywood, fabric or metal about which the veneer strips are wrapped, as above described, In this instance, however, suitable recesses must be provided in the pressure applying clamps to accommodate the rib or bulge, indicated at II4, produced by the collar. Heat and pressure thereupon will form the plywood strips Wrapped thereabout so that when the tubing is removed from the pipe, the reinforcing collars will be imbedded therein.

Similarly, and wherein required, the ends of the tubing 'may be flared, as illustrated in Figs. 6 and 7, by providing a corresponding form therefor; indicated at I I5. This form will'provide the tubing with a flared mouth at one or both ends thereof, as indicated at IIB.

The flared mouth IIB at the ends of the tubes may be utilized for joining sections of the tubing together, as shown in Figs. 8 and 9. The abutting flared ends of the tubing will provide a peripheral bulge which will permit interlocking with the coupling indicated at II'I, which may be in the form of pressed veneer or a fabric cemented about the adjacent ends of the tubing and interlocking with the flared ends thereof byl the thermo-setting glue. The end forms II5 may be removed, if desired, or, as shown in Figs. 8 and 9. they may be retained within the flared ends of the tubing for reinforcing purposes.

In Fig. 9 the joined ends of the tubing may be further reinforced by the cylindrical block IIS secured within the formsl II5 through which medium the ends of the tubingwill be interlocked and secured.

As illustrated in Fig. 10, a continuous three ply tubing vvmay be formed, comprising an inner ply 2II, an outer ply 2I2, and an intermediate ply 2I3, having its grain running transversely of the inner and outer plies. Said plies are spirally wound in opposite directions, respectively, about two sections of aligned pipe having their ends abutting a block 2I8, said block having reduced portions 2I9 extending into the respective adjacent ends of the pipe and being provided with a steam passage220. The extended periphery of the block may be formed with a bead 22| about which the veneer strips are formed and pressed to leave the bulge 222 therein. Where desired,

end blocks 223 may be secured within the open l Y i Similar arrangements of internally positioned blocks may be employed wherein the use to which the tubing is put requires nailing at spaced intervals.

As illustrated in Fig. ll, one end of the tubing may be closed by a disk 323by forming and pressing the veneer strips about its periphery which may be provided with an interlocking bead 324, the'disk being glued therein. In such manner suitable containers or tumblers may be produced. V

As illustrated inf-Fig. 12, the tubing may be of conical or tapered form for various purposes, that illustrated herein being employed as a cup having the bottom closed by a plug 423.

Fig. 13 is further illustrative of the conical or tapered form of tubing H), whereby a continuous line of tubular sections may be formed by tele- .scoping the ends.

In Fig. 14 there is diagrammatically illustrated a method of continuously forming tubing SII,

of any desired length. Thus, in laying a pipe line the tubing may be formed on the ground where it is to be laid without joints, by continuously progressing .with its formation. In this connection there is provided a steam pipe GII having one end closed and the other end provided with a steam inlet SI5 and an outlet BIG. A suitable pull rod SI1 is provided for pulling thesteam pipe forwardly to form a new portion of the tubing after completing the formation of the preceding portion thereof. Any suitable clamping device, such as illustrated in Figs. 4 and 5, may be employed for applying external pressure to each portion of the tube as it is being formed while steam is introduced into the pipe 6M. The pressure may be exerted-by such clamping device by means of screws, toggles or the like in any well known manner, instead oi?` by steam pres-f sure.l Asl fast as one portion of the tubing is completed, the external` pressure may be released, the pipe 6M pulled therefrom and again wrapped to form the succeeding portion, after which the pressure and heat may again be applied; These operations may continue indefinitely for producing a continuous length of tubing without joints.

ception of steam, as distinguished from the heat- Said member may be in the form of hard or sponge rubber, or may be a pneumatic rubber bag into which air, steam, oil or water is introduced for expanding the bag. Thus. the pressure may be equalized and exerted radially inwardly against the entire circumference of the tubing. Furthermore, the heat may be applied, as well as the pressure, through themedium'of the bag Zia wherein steam, hot water or oil is introduced.

Whereas the tubing has been herein illustrated as cylindricalor circular in cross section, it is obvious that it may ,be of various other cross sectional shapes, such as oval or rectangular v with rounded edges or the like, as illustrated in Fig. 15. ,-Thus, other tubular shapes similarly formed vand constructed are provided which may be suitable for the production of sections of fuselage of airplanes, wings, pontoons, simulation of logs for log cabin construction and the like. In

such structural formation, the outer surface may be highly decorated, since ne veneers may be Whereas one example has been above described in respect to producing the tubing vwherein exterior presses are employed for exerting pressure thereabout, it may be mentioned that an alter-- used with decorative efgects produced by the natural wood grains. Also, it may be noted that the tubes being hollow, provide excellent insulation in building and similar structural work.

The tubing may be 4developed to any desired number of plies,- generally from two to ve. How,- ever, an exceptionally strong structure for its thickness is gained by using three plies (Fig. l0) and wherein the intermediate ply is formed with the grain of its strip extending transversely to the grain of the inner and outer plies. This arrangement is of a character to prevent normal distortion due to the neutralization of the ten- I sion set up by the spiral winding.

The invention claimed is:

l. A. tubular multi-ply structure formed of wood veneer strips spirally wound in opposite directions one upon the other, said winding being formed with an annular enlargement to provide an internal recess, and a localized reinforcing member seated-within said formed recess in interlocking engagementwith said strips.

2. A tubular multi-.ply vstructure formed o! wood veneer .strips spirally wound in opposite directions one upon another, said winding being formed to provide a peripheral rib comprising an outer surface enlargement and an inner surface.

recess, a thermo-setting resin glue binder therevfor, and a reinforcing closure member seated ithin` said structure and interlocking with said 

